CHARGER

PURPOSE:To prolong the service life of a Ni-Ca battery by starting the charging operation only when the voltage of the Ni-Ca battery drops below a predeter mined level through discharge thereby preventing the memoryode effect. CONSTITUTION:A charging circuit 7 feeds power to a Ni-Cd battery 2 under control of a CPU 9 thus conducting the boosting charge. After the battery voltage reaches a peak value Vp, a decision is made whether the voltage has dropped by DELTAV and if the voltage has dropped by DELTAV, the CPU 9 controls the charging circuit 7 to interrupt the charging power supply to the Ni-Cd battery 2. Subsequently, the CPU 9 sustains interruption of the charging power supply until the battery 2 voltage drops down to a predetermined charge restart voltage Va through discharge and then starts recharging operation. This procedure prevents memoryode effect and prolongs the service life of battery.